I think since it's an event aimed mainly at people who won't already have an Amiga to buy expansions or software for you might want to take as many full A1200 systems as you can fit so when attendees walk past and see the nostalgic Amiga games running on your demo systems (I hope you'll have a couple of Amigas set up for people to play on too) they might be tempted enough to take the plunge and purchase an Amiga for themselves. Then you get to suggest all the essentials like 42Mhz accelerators and Compact Flash adapters. Other than that, take anything that might appeal to a broad audience like those USB Competition Pro joysticks, and of course any Amiga games that'll fit with the rest of the stock, I'm sure a couple of attendees will still have an Amiga packed away at home they'd be willing to dig out if they had some new games to try on it.